CN1849092A - Bioimpedance methods and apparatus - Google Patents

Abstract

Methods and apparatus for providing bioimpedance analysis are provided. In certain aspects, equivalent circuit frequency response models are provided which lead to improved correlations with MRI data. The frequency response models take account of body composition, including the fat component of a body segment. Data obtained by performing bioimpedance spectroscopy (BIS) and MRI on the calves of subjects illustrates the improved correlations achieved compared to single frequency analyses at 50 kilohertz and analyses performed using the conventional Cole-Cole model.

Description

Bioimpedance method and instrument

Mutual reference with relevant provisional application

The application requires the U.S. Provisional Application No.60/502 of JIUYUE in 2003 submission on the 12nd, the U.S. Provisional Application No.60/580 that on June 16th, 483,2004 submitted to, 166, and on July 14th, 2004 the U.S. Provisional Application No.60/587 that submits to, 652 rights and interests under 35USC § 119 (e).The content of all these provisional application is all included this paper in full in.

Technical field

The present invention relates to bioimpedance method and instrument, more specifically, relate to these methods of application and instrument and come the muscle content of determination object body segment, fat content, and/or the purposes of extracellular fluid content, wherein this sections can comprise the whole health of this object basically.

Background technology

For a long time, the electrology characteristic of biological tissue causes scientific concern always.In eighties of last century, much biology and biomedicine field have been applied to based on the progress of bio electricity knowledge and new device.

The bio-electrical impedance analysis is one of interesting and challenging problem in this field.Because having with Noninvasive, simple, cheap and portable method, bio-impedance detects the potentiality that health is formed, so bio-impedance is conducted a research in a lot of fields of medical science.Particularly, bio-impedance was applied to clinical research a lot of years.For example, Nyboer[3] and Patterson[4] reported that bio-impedance is applied to clinical initial stage.

A lot of authors have studied the essence [2,4,5] of living tissue electrology characteristic.Usefulness multifrequency electric currents such as Schwan have been described the relation [2] between the cell membrane insulation characterisitic.Cole has set up well in order to explain the basic theories [1] of in-vivo tissue electrology characteristic.Particularly, Cole has successfully set up a kind of equivalent-circuit model (hereinafter referred to as " Cole-Cole model ") to explain the electroresponse to the AC electric current of cell and cell membrane thereof.

Based on Cole-Cole model and Hanai method [5,6,10], a kind of method of bio-impedance frequency spectrum (BIS) of utilizing has been proposed to be used in measurement extracellular liquid volume (ECV) and intracellular fluid body volume (ICV).Now, multifrequency bioimpedance analysis method can provide some information about extracellular fluid and intracellular fluid volume in the health compartment total or sections.

Yet the accuracy that comprises the bioimpedance analysis of BIS is the focus [7,8] that clinical user is paid close attention to.Utilize bioimpedance analysis to assess body fluid although a lot of researchs have been reported, because reliability, problem that effectiveness is relevant with accuracy, prior art is also being widely accepted in clinical practice.

Measurement and analysis for utilizing existing bio-impedance technology have several factors that its accuracy is caused harmful effect.According to some aspect of the present invention, the present invention relates to one of them factor, that is, be used to analyze the model of bio-impedance data.The bio-impedance model of Chang Yong calculating different tissues electrology characteristic all has a basic hypothesis so far, and promptly with respect to fat free part, fat has higher resistivity, therefore can ignore fat lump.Yet nearest discovering when tested object has significant quantities of fat and organizes is in 50 kilo hertzs of biological impedances that carry out can be affected [7].As detailed below,, found that when measuring the health composition with BIS, the quantity of fat is one of key factor that influences its accuracy for tested object with different body-mass indexes (BMI) value according to the present invention.

Summary of the invention

According to first aspect, the invention provides a kind of method that is used for the bio-impedance data of analytic target body segment, described body segment has the outer skin surface, and described method comprises:

(a) alternating current of a plurality of frequencies is put at least two points on outer skin surface, so that electric current passes this sections;

(b) for each frequency, the voltage difference between at least two other points in record outer skin surface, the voltage difference of described record comprise amplitude and mutually information (that is, and amplitude and be worth mutually or, considerably, resistance and reactance value); (c) the voltage difference that is used in a plurality of frequency records determines to show at least one numerical value of muscle, fat and/or the extracellular fluid content of this sections, described numerical value is to determine with the impedance model of this sections, this impedance model comprises three parallel circuit at least, and one of them circuit is by resistor R _IWith capacitor C _MBe composed in series, it mainly represents the muscle composition of this sections, and a circuit is by resistor R _FWith capacitor C _FBe composed in series, it mainly represents the fat constituent of this sections, and another circuit is made up of resistor.

According to second aspect, the invention provides a kind of method that is used for the bio-impedance data of analytic target body segment, described body segment has the outer skin surface, described method comprises: (a) alternating current of a plurality of frequencies is put at least two points on outer skin surface, so that electric current passes this sections; (b) for each frequency, the voltage difference between at least two other points in record outer skin surface, the voltage difference of described record comprise amplitude and mutually information (that is, and amplitude and be worth mutually or, considerably, resistance and reactance value); (c) the voltage difference that is used in a plurality of frequency records determines to show at least one numerical value of this sections fat and/or extracellular fluid content, described numerical value is to determine with the impedance model of this sections, this impedance model comprises two parallel circuit at least, and one of them circuit is by resistor R _FWith capacitor C _FBe composed in series, it mainly represents the fat constituent of this sections, and another circuit is made up of the resistor of this sections extracellular fluid composition of main representative;

Wherein: (i) described two parallel circuit are only parallel circuit in this impedance model, and it represents the composition of skin inner segment; (ii) each frequency that applies in the step (a) is less than or equal to 10 kilo hertzs.

Some embodiment of aforementioned aspects according to the present invention adopts a dependency equation, and it is with model parameter (for example, R _F) be converted into physiology's numerical value (for example, fat content value) of this sections.This dependency equation can obtain by following steps: (i) carry out step (a) on a plurality of calibration object, (b) with (c) to obtain the model parameter value of described each object; (ii) on the sections of described a plurality of calibration object, measure (for example, measuring fat content) to obtain the physiological values of described each object sections with nuclear magnetic resonance; (iii) step (i) and the (ii) middle numerical value that obtains are carried out regression analysis to obtain the dependency equation.

Preferably, described a plurality of calibration object comprise at least one body-mass index less than 20 object and at least one body-mass index greater than 35 object.More preferably, described a plurality of calibration object comprise at least one body-mass index less than 20 object and at least one body-mass index greater than 40 object.

According to the third aspect, the invention provides a kind of method that is used to measure the girth of a body segment part that covers by skin, this method comprises: (a) use a series of electrodes around described part, described a series of electrode has first electrode and the most last electrode, in described a series of electrodes, except that first and the most last distance between electrodes, the circumferential distance between all electrodes all is known; (b) by applying substantially the not low-frequency current of transdermal, measure in described a series of electrode except that first and the most last electrode resistance between at least two electrodes; (c) determine the resistivity of skin per unit length by known circumferential distance between the resistance measured in the step (b) and two electrodes; (d) by applying substantially the not low-frequency current of transdermal, measure in described a series of electrode first and the most last electrode between resistance; (e) calculate in described a series of electrode first and the most last distance between electrodes by the resistivity of the per unit length measured in the resistance that records in the step (d) and the step (c).

Should understand above describe, in general terms and the following detailed description all is example of the present invention, is intended to be provided for understanding the general view or the framework of the present invention's essence and characteristics.

Listed other features and advantages of the present invention in the following detailed description, from these are described, those skilled in the art will readily appreciate that the feature and advantage of part, perhaps confirmed by implementing invention as herein described.

Comprise that accompanying drawing further understands the present invention to provide, these accompanying drawings are included this description in and are formed the part of present disclosure.

Brief Description Of Drawings

Fig. 1 shows that existing cross-sectional form (Figure 1A) also has three dimensional form (Figure 1B) according to health composition model of the present invention.

Fig. 2 A and 2B are the equivalent circuit frequency response models that is used for Fig. 1 health composition model.

Fig. 3 is under the low frequency condition, for example is lower than under 10 kilo hertzs of conditions, is used for the equivalent circuit frequency response models of Fig. 1 health composition model.

Fig. 4 demonstration can be used for implementing electrode structure of the present invention.

The resistor model of Fig. 5 displayed map 4 electrode structures.

Fig. 6 shows that the electrode of the bio-impedance data be used to produce following embodiment places.

Fig. 7 shows the dependency between the ρ value of measuring and calculate with equation 12 and 13 gained.More precipitous with the dependency gradient that equation 12 obtains, this shows the measurement for bio-impedance, includes the fat content relevant information in the equivalent circuit frequency response models value.

Fig. 8 shows the p value of the t test between the group of objects with different fat contents.

Fig. 9 shows the curve fitting of the impedance of three objects (patient) with different fat contents.

Figure 10 shows that fat mass is 0.588 kilogram the impedance magnitude (Figure 10 A) of object (patient) and (Figure 10 B) mutually of impedance.

Figure 11 shows that fat mass is 0.134 kilogram the impedance magnitude (Figure 11 A) of object (patient) and (Figure 11 B) mutually of impedance.

Figure 12 shows the dependency between muscle (MS) assessment of making of MRI and BIS of the present invention.

Figure 13 shows muscle quality and the dependency between 5 kilo hertzs of resistance that records that MRI records.

Figure 14 is the muscle quality that records of (i) MRI and hinder (R with the endocellular electricity of multifrequency of the present invention, three parallel circuit model determinations relatively _I) between dependency (Figure 14 A) and the (ii) muscle quality and the dependency between 50 kilo hertzs of impedances that record (Figure 14 B) that record of MRI.

Figure 15 is the muscle quality that records of (i) MRI and with the fatty resistance (R of multifrequency of the present invention, three parallel circuit model determinations relatively _F) between dependency (Figure 14 A) and the (ii) muscle quality and the dependency between 50 kilo hertzs of impedances that record (Figure 14 B) that record of MRI.

Figure 16 is the muscle quality that records of (i) MRI and hinder (R with the endocellular electricity of multifrequency of the present invention, three parallel circuit model determinations relatively _I) between dependency (Figure 16 A) and the (ii) muscle quality that records of MRI and with the dependency (Figure 16 B) between the endocellular electricity resistance of Cole-Cole model determination.

Figure 17 is the muscle quality that records of (i) MRI and with the fatty resistance (R of multifrequency of the present invention, three parallel circuit model determinations relatively _F) between dependency (Figure 17 A) and the (ii) muscle quality that records of MRI and with the dependency (Figure 17 B) between the endocellular electricity resistance of Cole-Cole model determination.

Detailed description of the present invention and preferred implementation thereof

As mentioned above, the present invention relates to bioimpedance method and instrument, it can provide about object, i.e. human or animal, the information of fat, muscle and/or extracellular fluid content of body segment.

Common described sections be the object limbs partly or entirely, for example, the shank of object or forearm, but also can be the object trunk partly or entirely, for example, the object abdominal part partly or entirely.Similarly, described sections can be as small as the part of concrete muscle or muscle, can be the whole body of object basically greatly extremely also.

The position of described sections and big young pathbreaker are depended on the placement of the electrode that applies electric current on subject's skin.Particularly, this sections will be formed the part of subject's body, and when the electrode that applies electric current was activated, a large amount of electric currents were through this sections.Suitable number, position and the polarity of the electrode by selecting to apply electric current can realize multiple current-mode in subject.In fact, by changing the selected polarity that applies the electrode of electric current, need not move the electrode that applies electric current and can analyze a plurality of sections.

As known in the art, the electrode of record electromotive force is usually located at the inboard of the electrode that applies electric current, that is, the electrode of record electromotive force is usually located at when the electrode that applies electric current is activated, and has on the skin around the patient body part that a large amount of electric currents pass through.

Use and the available bio-impedance equipment of the record of electromotive force of electric current carry out, the electric current that comprises known or follow-up research and development applies electrode and recording electrode, for example, can be by the equipment of commercial sources acquisition, as 4000B bio-impedance spectrum analyzer system (Xitron Technologies used among the following embodiment, Inc., SanDiego, CA).Perhaps, can when enforcement is of the present invention, use the equipment of customization.

The processing of the data that obtain with bio-impedance equipment can be carried out in this equipment or carry out with independently computer is online fully.Perhaps, can be with data-storing and processing after measurement.

Preferably, bio-impedance equipment comprises a microprocessor, makes this microprocessor finish the part of analysis programme of the present invention at least by programming.For example, bio-impedance equipment can be applied to the regression equation of calibration object being studied acquisition the impedance data that records from certain object, thereby directly fat, muscle and/or the extracellular fluid content of this object is reported to the user of this instrument, this object oneself and/or for example to interested other people of this information, for example health care worker.The report form of fat, muscle and/or extracellular fluid content can be chart, numeral (for example percent of fat and/or muscle), color (for example, high fat content is reported as redness), or the like.

In some embodiment of the present invention, the alternating current of a plurality of frequencies is applied on the subject's skin.Preferably, use 10 frequencies at least, more preferably, approximately use about 50 frequencies.Preferably, a plurality of frequencies comprise the frequency of 5-1000 kilohertz, though also can use super large or extra small frequency range if necessary.Most preferably, these frequencies are the logarithm distribution in frequency range.

As mentioned above, there are a lot of problems in the bio-impedance model of calculating different tissues electrology characteristic commonly used so far.One of these problems are the basic assumptions of this model, and promptly fat has high resistivity with respect to not fatty part, so fat lump can be left in the basket.Another problem is relevant with the endocellular electricity resistance with the extracellular of this Model Calculation.Though not explanation can be subjected to the influence of skin and fatty tissue content based on the model of skin undertissue in existing model.

The present invention relates to by checking different health constituent,,, reduce the variety of issue of existing analytical method the response of signal of telecommunication input as skin, fat, muscle.More specifically, according to its some aspect, the invention provides model with effect with the systemic heterogeneity of equivalent circuit description.

Particularly, in order to improve the prior biological resistance technique, some aspect according to the present invention provides a kind of improved electrical model, the effect of the systemic electrology characteristic of its soluble different proportion and a lot of power frequencies.Data shown in the following embodiment 1 have specifically been estimated the resistivity that records on the skin and with the relation between the resistivity of this Model Calculation in the time of 5 kilo hertzs.

Fig. 1 shows according to body segment composition model of the present invention, can be used for describing the conductive compositions of limbs.Particularly, this figure shows the conductive compositions in the limbs sections, and they have formed the basis of electrical model of the present invention.As a reference, the electrology characteristic (dielectric coefficient and resistivity) of different tissues during the power frequency of 10 kilo hertzs of usefulness that table 1 shows as previous research [8] is reported.

Fig. 2 has shown equivalent-circuit model, the wherein R of Fig. 1 _GRepresentative is with two resistance that electrode records on the skin, R _s, R _F, R _E, R _IAnd R _BRepresent the resistance of the long-pending and bone of skin, fat lump, extracellular volume, intracellular respectively.Among Fig. 2 A, C _IN, C _FAnd C _MRepresent the electric capacity between skin and the electrode respectively, the electric capacity of fat and the electric capacity of cell membrane.

According to the model of Fig. 2 A, total current (I _G) can provide by following formula:

I _G=I _S+ I _F+ I _E+ I _I+ I _B Equation 1

Stride across R _GElectromotive force can obtain by following formula:

$R_G{I}_G=R_E{I}_E+\frac{2I\′G}{\mathrm{\ω}{C}_{\mathrm{IN}}}$ Equation 2

I ' wherein _GBe by capacitor C _INElectric current, provide by following formula:

I ' _G=I _F+ I _E+ I _I+ I _B Equation 3

Because skin resistance (R _s) high more a lot of than the resistance of other tissue, so I _sVery low, thus we obtain:

I ' _G≈ I _GEquation 4

Because (for example, 5 kilo hertzs) electric current is not by space in the cell, so can transform this equivalence circuit as shown in Figure 3 for low frequency.

Among Fig. 3, E represents between two measurement electrode and (strides across R _G) electromotive force, E _ERepresentative strides across R _EElectromotive force.Therefore, can write out following electromotive force equation:

$E=E_E+\frac{2I_G}{\mathrm{j\ω}{C}_{\mathrm{IN}}}$ Equation 5

Parameter wherein Representative strides across capacitor C _INElectromotive force.High or work as C when power frequency _INCan ignore this electric current when big.

According to the parallel circuit of Fig. 3, the resistance R that measures by skin electrode _GCan pass through following equation meter

Calculate: $R_G=\frac{R_E(\frac{1}{\mathrm{j\ω}{C}_F}+R_F)}{R_E+\frac{1}{\mathrm{j\ω}{C}_F}+R_F}+\frac{2}{\mathrm{j\ω}{C}_{\mathrm{IN}}}$ Equation 6

Reactance (the X of fat lump _F) and skin and electrode between electric capacity (X _IN) as follows:

$X_F=-\frac{j}{\mathrm{\ω}{C}_F},X_{\mathrm{IN}}=-\frac{j}{\mathrm{\ω}{C}_{\mathrm{IN}}}$

Therefore, R _GCan be reduced to:

$R_G=R_E(1+\frac{R_E/{\mathrm{<figure-callout\; id="1"\; label="X\; F"\; filenames="A20048002630100342.png"\; state="\{\{state\}\}">X</figure-callout>}}_F}{1+(R_E+R_F)/X_F})-2X_{\mathrm{IN}}$ Equation 7

With $R_G=R_E(1+\frac{A_F}{\frac{{\mathrm{\&rho;}}_F}{{\mathrm{\&rho;}}_E}{A}_E+A_E})-2X_{\mathrm{IN}}$ Equation 8

A wherein _FAnd A _ERepresentative derives from the cross-sectional area of ECV in the fat lump cross-sectional area of MRI and this sections respectively.According to previous research, the ratio of resistivity and ECV resistivity is about following [6] in the fat lump.

$\frac{{\mathrm{\&rho;}}_F}{{\mathrm{\&rho;}}_E}\&ap;3-5$ Equation 9

Equation 8 can further be reduced to

${\mathrm{\&rho;}}_G={\mathrm{\&rho;}}_E\frac{A_G}{A_E}(1+\frac{A_F}{A_G})-2X_{\mathrm{IN}}\frac{A_{\mathrm{<figure-callout\; id="10"\; label="G\; L\; Equation"\; filenames="A20048002630100342.png,A20048002630100352.png"\; state="\{\{state\}\}">G</figure-callout>}}}{L}$ Equation 10

ρ wherein _GBe the resistivity that measures on the skin, ρ _EBe the spatial resistivity of ECV, it is a constant i.Make following equation:

$k_E=(1+\frac{A_F}{A_G})$ Equation 11

And hypothesis Little, we obtain:

${\mathrm{\&rho;}}_{G,\mathrm{Cal}}=k_E{\mathrm{\&rho;}}_E\frac{A_G}{A_E}$ Equation 12

If k _E=1, can calculate electrical conductivity by following formula:

${{\mathrm{\&rho;}}^{*}}_{G,\mathrm{Cal}}={\mathrm{\&rho;}}_E\frac{A_G}{A_E}$ Equation 13

Below in embodiment 1, listed these equations, specifically be that equation 12 and 13 is applied to the experimental data that obtains from one group of calibration object.The volume of these presentation of results fat lumps as herein described is material impact factors when forming with four electrode bio-impedance technology assessment healths of standard.

The experimental data of embodiment 1 be by applying a kind of frequency electric current promptly 5 kilo hertzs electric current obtain.The equivalent-circuit model of body segment composition of the present invention is preferably used for describing the response to the multifrequency electric current.Embodiment 2 shows the result of this multifrequency test.Particularly, this embodiment has shown the object with different fat contents when power frequency increases, and the resistance of its impedance reduces the difference of situation.

Fig. 2 B is that of Fig. 2 A equivalent-circuit model improves version.Among Fig. 2 B, Z _AlwaysRepresentative is in two total impedances that electrode measurement arrives of A and B.As Fig. 2 A, R _S, R _F, R _E, R _IAnd R _BRepresent the resistance of the long-pending and bone of skin, fat, extracellular and intracellular respectively, C _IN, C _FWith ℃ _MRepresent the electric capacity of electric capacity, fat lump electric capacity and cell membrane between skin and the electrode respectively.R _I1And R _I2The resistance of the body segment between representative injection and the measurement electrode.

For Fig. 2 model being obtained relation based on frequency, with this model of equation simplification, thereby with its standardization.The first, we use R _PRepresent R _EAnd R _BParallel resistance:

$R_P=\frac{R_E\&times;R_B}{R_E+R_B}$ Equation 14

The second, we simplify calculating with following parameters a, b, c and d:

A=R _IR _FC _IC _FEquation 15

B=C _IC _F(R _I+ R _F) equation 16

C=C _FC _IEquation 17

D=C _F+ C _IEquation 18

All-in resistance (Z _Always) can obtain by the circuit of Fig. 2, provide by following equation 19:

Equation 19

For with equation 19 standardization, we make

μ=C _IN[R _S(a+bR _P)+aR _p] equation 20

Z then _AlwaysProvide by following equation 21:

Equation 21

Represent with one group of parameter preferably that the function of each composition comes each object frequency response data is carried out quantitative analysis in the equivalent circuit.Such one group of data help the standard transfer function is used for analyzing, thereby help to differentiate the difference of each subject's body composition.

For example, can be with relation of plane standardization, wherein P under equation 21 usefulness ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂, Q ₃Be one group of parameter:

Equation 22

R with each patient of following Equation for Calculating (each object) _I, R _F, C _I, C _F, R _P, R _S, C _INValue:

$P_l=\left(\frac{1}{\mathrm{\&mu;}}\right)a{C}_{\mathrm{IN}}{R}_P{R}_S=\frac{a{C}_{\mathrm{IN}}{R}_P{R}_S}{C_{\mathrm{IN}}[R_S\left(a+b{R}_P\right)+a{R}_P]}=\frac{a{R}_P{R}_S}{R_S(a+b{R}_P)}+a{R}_P$ Equation 23

${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="A20048002630100311.png,A20048002630100312.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=\frac{1}{\mathrm{\&mu;}}{R}_S[(2+C_{\mathrm{IN}})b{R}_P+2a]=\frac{R_S[(2+C_{\mathrm{IN}})b{R}_P+2a}{C_{\mathrm{IN}}\left[R_S(a+b{R}_P)\right]+a{R}_P}$ Equation 24

${\mathrm{<figure-callout\; id="3"\; label="P"\; filenames="A20048002630100291.png"\; state="\{\{state\}\}">P</figure-callout>}}_3=\frac{R_S}{\mathrm{\&mu;}}{R}_S\left[(C_{\mathrm{IN}}c{R}_P+2b+2d{R}_P)\right]=\frac{R_S\left[(C_{\mathrm{IN}}c{R}_P+2b+2d{R}_P)\right]}{C_{\mathrm{IN}}[R_S(a+b{R}_P)+a{R}_P]}$ Equation 25

$P_4=\frac{2R_S}{\mathrm{\&mu;}}=\frac{2c{R}_S}{C_{\mathrm{IN}}[R_S(a+b{R}_P)+a{R}_P]}$ Equation 26

${\mathrm{<figure-callout\; id="1"\; label="Q"\; filenames="A20048002630100342.png"\; state="\{\{state\}\}">Q</figure-callout>}}_1=\frac{1}{\mathrm{\&mu;}}[R_S{C}_{\mathrm{IN}}(d{R}_P+b)+b{R}_P(2+C_{\mathrm{IN}})+2a]=\frac{[R_S{C}_{\mathrm{IN}}(d{R}_P+b)+b{R}_P(2+C_{\mathrm{IN}})+2a]}{C_{\mathrm{IN}}[R_S(a+b{R}_p)+a{R}_P]}$ Equation 27

${\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="A20048002630100311.png,A20048002630100312.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2=\frac{1}{\mathrm{\&mu;}}[c{R}_S{C}_{\mathrm{IN}}+(c{C}_{\mathrm{IN}}+2d)R_P+2b]=\frac{[c{R}_S{C}_{\mathrm{IN}}+(c{C}_{\mathrm{IN}}+2d)R_P+2b]}{C_{\mathrm{IN}}[R_S(a+b{R}_P)+a{R}_P]}$ Equation 28

${\mathrm{<figure-callout\; id="3"\; label="Q"\; filenames="A20048002630100291.png"\; state="\{\{state\}\}">Q</figure-callout>}}_3=\frac{2c}{\mathrm{\&mu;}}=\frac{2c}{C_{\mathrm{IN}}[R_S(a+b{R}_P)+a{R}_P]}$ Equation 29

Wherein a, b, c and d in the above-mentioned equation 15-18 definition.

In these equations, R _I, R _F, C _I, C _F,R _P, R _S,C _INBe that variable to be determined, P are arranged ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂, Q ₃It is this patient's data value that the curve fitting with certain patient's frequency response data obtains.Particularly, certain patient's seven variable R _I, R _F, C _I, C _F, R _P, R _S, C _INBe P with this patient ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂, Q ₃Value separates that above-mentioned seven equations (equation 23-equation 29) obtain.

Among the embodiment 2 below, obtain certain patient's parameter P with the curve fitting procedure of MATLAB workbox (The MathWorks, Inc., Natick, Massachusetts) ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂, Q ₃Obtain the simulation (simulation) of frequency response curve with the standard signal handling procedure in MATLAB workbox.

Though when being applied to the frequency response data type of acquisition in the bio-impedance experiment, equation 22 is preferred curve fitting equations, it should be apparent to those skilled in the art that from present disclosure if desired, also available other curve fitting equation.Similarly, except that the MATLAB program, other Mathematical treatment program also can be used for implementing the present invention.

But manual measurement sections length and girth.Perhaps, according to some embodiment of the present invention, the girth of sections and length avaivable electrode group rather than single electrode are measured (see figure 4).(for example,＜10 hertz, the resistance in the time of preferably＜1Hz) can reflect the electrology characteristic of skin to low frequency.Because the distance between every pair of any two adjacent electrode is known, the girth of measured zone can followingly calculate,

$C=D\&CenterDot;(n-1)+\frac{R_n}{\mathrm{\&lambda;}}$ Equation 30

Wherein C represents girth, and n is an electrode number, and D is a known distance between two adjacent electrodes, R _n(n=8 among Fig. 5) forms resistance between when ring first and the most last electrode when electrode on any sections, λ is the ratio between resistivity and the cross-sectional area, can followingly calculate

$\mathrm{\&lambda;}=\frac{1}{n-1}\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}\frac{R_i}{D_i}$ Equation 31

R wherein _iBe except that first and the most last electrode resistance between any adjacent two electrodes, D _iBe except that first and the most last electrode any adjacent two distance between electrodes.

Therefore, the concrete resistivity of this sections skin is

ρ '=λ * A equation 32

Wherein A is the cross-sectional area of this sections.Because A=C ²/ (4* π), ρ ' can be calculated by following formula

ρ '=λ * C ²/ (4* π) equation 33

In case determined the skin resistance rate, length can be by following Equation for Calculating

L=A*R _L/ ρ ' equation 34

Wherein, L is a length, and A is the cross-sectional area of this sections, and R _LBe along the resistance between two cross sections of this sections longitudinal axis.

In Fig. 4, E1-E8 is an electrode, and D1-D7 represents two distances between the adjacent electrode respectively, and D1=D2=...=D7.Among Fig. 5, R1-R7 represents the skin resistance between adjacent two electrodes.R8 is the resistance between first electrode (E1) and the most last electrode (E8) as mentioned above.Distance between E1 and the E8 is unknown, but as mentioned above, can be calculated by R8/ λ, and therefore, girth (C) can be calculated by equation 30.

Mathematical operations as herein described can be carried out with multiple computer and software.For example, the available MATLAB program that can obtain by commercial sources as mentioned above and the being configured to PC of moving this program by this program manufacturer's description is carried out these operations.Being customized to its concrete form of program that is used to implement mathematical operations of the present invention can be a product that comprises computer usable medium, as the disk that wherein is composed of this program, CD etc.The data that produce with these programs can be stored on various types of storage mediums similarly.

Be not meant to and limit the present invention by any way, will come the present invention is done description more fully with the following examples.

Embodiment 1

Fat lump is to the influence of bioimpedance analysis

This embodiment explanation is formed when measuring health with bioimpedance analysis, comprises that when measuring body fluid in the clinical practice of dialysis patient, fat lump is a key factor that influences accuracy.

28 chronic hemodialysis patients are studied before treatment.Table 2 has been listed the relevant parameter of this group objects (patient).

(Xitron Technologies, San Diego CA) carry out the shank biological impedance with BIS device Xitron 4200.Electrode is placed step and is published in the previous research [9].As described therein, when object is in seat, measure the distance (H) at Patella core and ankle center, the outside, electrode is placed on the normal position (see figure 6).When patient's inertia, be placed on 5cm on the mid point M with one in two measurement electrode, another is placed on 5cm under the M.Be placed on 3cm on the measurement electrode with one in two electric current injecting electrodes, another is placed on 3cm under the measurement electrode.Girth with two measurement electrode places of ruler measurement shank of 0.1cm precision.

Under 5 kilo hertzs of frequency conditions that distribute to logarithm between 1 megahertz, with the resistance and the reactance of BIS measurement device shank.Calculate extracellular resistance (Re) and endocellular electricity resistance (Ri), the program that provides with the BIS device obtains ECV and ICV[9,10].Measure fat lump, muscle masses and the bone of the same area respectively with MRI.

Geometric volume (V _G) be defined as the cross-sectional area (A of this sections _G) multiply by length (L).A _GCan be by A _G=C ²/ (4 π) calculates, and wherein C is the meansigma methods of shank girth.Resistivity (ρ _{G, Mea}) calculate by following measured value:

${\mathrm{\&rho;}}_{G,\mathrm{Mea}}=\frac{R_G\&times;A_{\mathrm{<figure-callout\; id="35"\; label="G\; L\; Equation"\; filenames="A20048002630100331.png"\; state="\{\{state\}\}">G</figure-callout>}}}{L}$ Equation 35

R wherein _GThe resistance that records when being 5 kilo hertzs, A _GBe cross-sectional area, the length of all objects all is fixed as 10cm.

For compare and measure and when calculating the fat lump volume to the influence of resistivity value, according to fat lump (V _F) and geometric volume (V _G) ratio 28 patients are divided into two groups: IUGR high-fat diet group is defined as V _F/ V _G＞0.2, normal fat group is defined as V _F/ V _G≤ 0.2.Data represent with the form of meansigma methods ± SD, with Si Shi t test relatively from the same group data not.If p value＜0.05 thinks that then group difference is remarkable.

Table 3 shows this resistivity of two groups result relatively.ρ _{G, Mea}(p＜0.05), ρ _{G, cal}There are significant difference in (P＜0.005) and Δ ρ between (p＜0.05), yet, the ρ between two groups ^* _{G, cal}Do not find significant difference (table 3).ρ _{G, Mea}And ρ ^* _{G, cal}Between there were significant differences (p＜0.05=, but ρ _{G, Mea}And ρ _{G, cal}Between do not find significant difference.

Fig. 7 shows the association between the resistivity value that calculates and measure with equation 12 and 13.The resistivity (ρ that this figure explanation is determined by equation 35 based on measured value _{G, Mea}) and the resistivity (ρ that calculates with equation 12 _{G, cal}) between have the height dependency.Among Fig. 7, diamond symbols is represented ρ _{G, Mea}With the ρ that obtains by equation 13 ^* _{G, cal}Dependency (ρ ^* _{G, cal}=0.66 ρ _{G, Mea}+ 76.7, R ²=0.96), solid circles symbology ρ _{G, Mea}With with each k _EThe ρ that calculates with equation 12 _{G, cal}Dependency (ρ _{G, cal}=0.93 ρ _{G, Mea}+ 41.1, R ²=0.9).Though ρ ^* _{G, cal}And ρ _{G, Mea}Between dependency very high, but slope (diamond symbols) has only 0.66.With each k _EAfter equation 12 calibration, slope is 0.93 (solid circles), i.e. result well a lot (dependency increases greatly).

Be very important for understanding the associated biomolecule electrical phenomena for the understanding that between the resistivity that records on the skin and each subcutaneous tissue, concerns.Research before a lot of has shown the resistivity [6] of various biological tissues and organ with the method for directly measuring.Yet because Clinical detection carries out at skin surface, and the resistivity of different tissues calculates by a lot of theoretical models, and the reason that makes a mistake may be: individually between (1) electrode and the skin have different resistance interfaces; (2) difference of adipose tissue volume between the individuality, and (3) theoretical model does not comprise the difference variable of the anti-and fat lump of skin resistance between the individuality.

The invention provides a kind ofly with the model of fatty resistance variable in being included in, this model also can comprise interface variable between skin resistance variable and electric capacity.Table 3 shows when fat lump increases, and there were significant differences between resistivity (Δ ρ) during by 5 kilo hertzs of this Model Calculation and the measured value.This hint low frequency not only should be comprised by the resistivity value that records on the skin when (5 kilo hertzs) contribution from the extracellular fluid compartment also should comprise the contribution from the fat lump compartment.Fig. 7 shows, with each K _EAfter the calibration, this slope of a curve no better than 1 shown in solid circle, and this explanation value of calculation approaches measured value.The very important point it being understood that the transmutability of resistivity depends primarily on individual fatty volume in the healthy individual.Therefore, adopt this model,, can obtain correct information about ECV by measuring for example shank resistivity.Hydration parameter (being used for regulating the variable unusual hydration of dialysis patient) etc. all is very important to this information for providing accurately; This reaches suitable body weight with regard to allowing by remove unnecessary body fluid when dialysing.

In a word, this embodiment has illustrated aspects more of the present invention, and a kind of model that these aspects provide can be used as and is used in the basis that resistivity that skin surface measures is calculated the resistivity of different tissues.Promptly, this embodiment has illustrated aspects more of the present invention, the resistivity models that these aspects provide a kind of body segment that is used for bioimpedance analysis to form, wherein this model description in resistivity that skin surface records with by calculating the relation between the resistivity that the tissue of forming limbs obtains.

Particularly, in this embodiment, in a group objects, inject on the shank surface and carry out concrete analysis with 5 kilo hertzs electric current.This studies explanation, the resistivity value height correlation that resistivity that obtains with this Model Calculation and actual measurement obtain.In next embodiment, studied the response of system to the different frequency electric current.The next presentation of results of implementing can detect the resistivity of cell membrane with three parallel circuit models of the present invention.

Embodiment 2

Multi-frequency is analyzed

In order to improve existing BIS technology, a correct electrical model should be able to be explained the systemic electrology characteristic of different proportion under large-scale power frequency condition.The purpose of this research is measured on the skin of shank, to estimate the frequency response of equivalent-circuit model from 5 kilo hertzs to 1 megahertz.Fig. 2 B shows this equivalence circuit model.

To with embodiment 1 in same 28 chronic hemodialysis patients before treatment, study (seeing Table 2).Still (Xitron Technologies, San Diego CA) carry out the shank bio-impedance and detect, and the placement of electrode is (see figure 6) described in the embodiment 1 as above to use BIS device Xitron 4200.

Under 5 kilo hertzs of frequency conditions that distribute to logarithm between 1 megahertz, measure shank resistance and reactance with the BIS device.Fat lump quality, muscle masses quality and the bone of BIS measurement same area have been measured respectively with MRI.According to the fat lump quantity in the shank patient is divided into three groups, first group of (G1): fat＞0.4kg, second group (G2): 0.25＜fat＜0.4kg and the 3rd group of (G3): fat＜0.25kg.

There were significant differences for resistance, reactance and impedance between discovery G1 and the G3; Yet only there were significant differences (figure .8) during greater than 40 kilo hertzs in frequency between G1 and the G2.Curve-fitting results to the initial data of impedance under the different frequency condition (circle, trigonometric sum square) is shown in Fig. 9.The data correspondence of representing with circle be that fat lump quality that MRI estimates is 0.59 kilogram patient, and the square fat lump quality of representing respectively of trigonometric sum is other two patient's data of 0.29 kilogram and 0.23 kilogram, fat mass is also estimated by MRI.

From two patients' frequency response curve (A) with mutually the response (B) be shown in Figure 10 and 11, the fat mass that one of them patient is recorded by MRI is 0.55 kilogram, muscle quality is 1.046 kilograms, bone is 0.021 kilogram, the fat mass that another patient is recorded by MRI is 0.134 kilogram, muscle quality is 1.022 kilograms, and bone is 0.022 kilogram.

The impedance of clearly observing the little patient of fat mass is (Figure 11 A) that reduces in the frequency range of 1-10 kilohertz, yet when patient's fat mass was bigger, this curve almost was a constant in same frequency range.In addition, in the smallest point of phase, the amplitude of frequency is different between this two patient.

Figure 12 shows, the dependency (MS between the muscle (quality) that muscle (quality) that BIS estimates and MRI estimate _BIS=285*L ²/ Ri, wherein L (10cm) is the distance between each detecting electrode on patient's shank, Ri is the endocellular electricity resistance that goes out with Fig. 2 B Model Calculation).Calculate MS _BISThe time be to obtain as the numerical value 285 Ω-cm of muscle resistivity by regression analysis based on the MRI data.

When producing Figure 12, for each patient, by using the P that obtains from the frequency response data of this patient's measurement ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂And Q ₃The 23-29 that solves an equation determines Ri.Therefore Figure 12 shows, comes the frequency response of each composition of quantitative analysis equivalent circuit with one group of parameter, and it can be used for identifying the difference of individual subject health composition.

Studied the P of above-mentioned first group (G1), second group (G2) and the 3rd group (G3) ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂And Q ₃The difference of value.Table 4 shows P between G1 and the G2 ₁Value has significant difference (p＜0.05), and P between G1 and the G3 ₄Significant difference.Remove P ₁And P ₄Outside, in P and Q parameter, there is not significant difference.

The foregoing description 1 explanation can be subjected to the influence of fatty tissue with equivalent-circuit model measured resistivity on skin surface of Fig. 2.It is believed that this is that the bio-impedance technology influences one of a plurality of key factors of its accuracy when estimating health composition (as extracellular and intracellular fluid volume).Certainly, the accuracy of bio-impedance only is not subjected to the influence of fat mass, also is subjected to the influence of interface between electrode and skin or level of skin hydration.

In this embodiment, result shown in Figure 9 has proved the reduction that increases relevant impedance among the patient with different fat contents with power frequency.The patient's that fat mass is bigger impedance is greater than the less patient of fat mass.Simulation experiment (simulation) result with two patients of similar muscle quality and bone mass shows that frequency response curve is different in the frequency range of 0-1 kilohertz.Difference proof between Figure 10 and 11 depends on fat mass to the variation of the response curve of 0-1 khz frequency scope, and this variation will influence the evaluation that multifrequency bioimpedance analysis pair cell is outer and endocellular electricity hinders greatly.And, during when object has bigger fat mass, can produce error at the Discrepancy Description that responds smallest point mutually between two patients with 50 kilo hertzs of unifrequency bioimpedance method.

Shown in Figure 12 has a lot of important enlightenments with the dependency between the muscle evaluation that BIS and MRI did for clinical and other application.Therefore, as shown in the drawing, electrical model of the present invention is fine with the actual muscle quality dependency of measuring with MRI.Therefore this model makes people can only can measure individual subject (patient's) muscle quality with the electrical measurement of simple, cheap and Noninvasive.

Concrete muscle quality with this model determination will depend on for being used to carry out the selected particular location of electrode that BIS measures.For example, the data of Figure 12 are the data for whole Calf muscle.By electrode being placed on different positions, can measure for example part of Calf muscle, muscle quality as shank gastrocnemius part, perhaps, do not measure Calf muscle, but measure other muscle, muscle parts and/or muscle group, for example, can measure all or part of biceps brachii m. of object.If just need relative measurement, also can measure with bio-impedance as mentioned above.Perhaps, this type of dependency shown in Figure 12 can obtain by biological impedance and the MRI measurement to concrete muscle, muscle parts or muscle group, thereby make this electrical measurement that " definitely " value of muscle quality can be provided, wherein " definitely " is worth the corresponding numerical value of numerical value preferred and with the MRI acquisition, and the numerical value that obtains with MRI is " golden standard " that be used for the muscle quality detection of generally acknowledging.

Can by suitably use electrode measure muscle masses, discrete muscle or muscle group (through or the checking that detects without MRI) have a lot of purposes.For example, these technology can be used in the degree of physical exercise of family, gymnasium, physical culture and Health Club, and be used to perform the operation and injured after rehabilitation, the effect of these situations and muscle quality increase is relevant.Therefore, by carrying out a series of biological impedance in the certain hour, object (patient) and/or its health care professional can be monitored the result of the variation of muscle quality as degree of physical exercise, changes in diet and/or rehabilitation programme.

Embodiment 3

Single low frequency biological impedance

Figure 13 is based on the plot of embodiment 1 and 2 data, lacks dependency between the resistance that muscle quality that it records when showing 5 kilo hertzs and MRI measure.Conclusion below these data are supported, promptly, when low frequency, the bio-impedance data of measuring are not corresponding with the muscle content of certain sections, but shown in the circuit model of Fig. 3, under these frequency conditions, be that fat and the extracellular fluid composition in the sections plays a major role to the measured value that obtains with bioimpedance method.

Embodiment 4

Comparative example

50 kilo hertzs of multifrequency, three parallel circuit model VS

Figure 14 and 15 is the comparisons between the dependency of dependency between the bio-impedance that obtains with the multifrequency of Fig. 2, three parallel circuit models and MRI measure and the impedance acquisition during with unifrequency (i.e. Chang Yong 50 kilo hertzs frequency).The data that are used for making these figure are and embodiment 1 and the 2 relevant data of above being discussed.

Figure 14 shows the muscle quality dependency, and Figure 15 shows the fat mass dependency.As shown in these figures, for muscle quality (R of the present invention ²During for the 0.6VS50 kilohertz 0.3) and fat mass (R of the present invention ²During for the 0.7VS50 kilohertz 0.2), multifrequency of the present invention, three parallel equivalent circuit frequency response models all obtain better dependency than single 50 kilo hertzs method.

Embodiment 5

Comparative example

Multifrequency, three parallel circuit model VS Cole-Cole models

Figure 16 and 17 be between the BIS that obtains with the multifrequency of Fig. 2, three parallel circuit models and MRI measure dependency and with the comparison between the dependency of Cole-Cole model acquisition.The data that are used for making these figure are and embodiment 1 and the 2 relevant data of above being discussed.

Figure 16 shows the muscle quality dependency, and Figure 17 shows the fat mass dependency.As shown in these figures, for muscle quality (R of the present invention ²For the 0.6VSCole-Cole model 0.4) and fat mass (R of the present invention ²For the 0.7VSCole-Cole model 0.1), multifrequency of the present invention, three parallel equivalent circuit frequency response models all obtain higher dependency than Cole-Cole model.

Though described and explained the specific embodiment of the present invention, should be understood that based on aforementioned disclosed content the improvement that does not much depart from the scope of the present invention with spirit is conspicuous for persons skilled in the art.Take a single example, though following claim has been recorded and narrated various feature of the present invention, be understood that the present invention contain these features arbitrarily and all combinations, and regardless of whether listing these combinations in the appended claims.

List of references

Below the above-mentioned various documents of quoting are listed in.Fit into this paper in these documents as a reference.

[1] K.S.Cole and R.H.Cole, " characteristic of dielectric propagation and absorption I. alternating current " (" Dispersion and absorption in dielectrics.I.Alternating current characteristics ") J.chem.Phys. the 9th volume, pp.341-351,1941

[2] H.P.Schwan, K.Li, " the electrolyte research on low electric conductance surface " (" A dielectric studyof the low-conductance surface membrane "), E.coli Nature the 177th volume, pp.134-135,1956

[3] J.Nyboer, impedance plethysmography (Electrical impedance plethysmography), the 2nd edition, Charles C.Thomas, Springfield, IL 1970

[4] R.P.Patterson, " impedance graphical method aroused in interest basis " (" Fundamentals of impedancecardiography "), IEEE Engineering in Medicine and Biology magazine. the 8th volume, pp.16-18,1989

[5] T.Hanai, " electrology characteristic of emulsion " (" Electrical properties of emulsions "), Emulsion Science, P.H.Sherman compiles, London:Academic, 1968, pp.354-477

[6] A.De Lorenzo, A.Andreoli, J.R.Matthie, and P.O.Withers, " predict the soma quality with theoretical method with bio-impedance: technology summary " (" Predicting body cell masswith bioimpedance by using theoretical methods:a technological review "), J ApplPhysiol the 82nd volume, pp.1542-1558,1997

[7] R.N.Baumgartner, R.Ross and S.B.Heymsfield, " fatty tissue influences bio-electrical impedance in the men and women of obesity? " (" Does adipose tissue influencebioelectric impedance in obese men and women? "), J Appl.Physiol. the 84th volume, pp.257-262,1998

[8] K.R.Foster and H.C.Lukaski, " whole body impedance-measurement what is? " (" Whole-body impedance-what does it measure? "), Am J Clin Nutr the 64th volume (supplementary issue), pp.388S-396S, 1996

[9] F.Zhu, S.Sarkar, C.Kaitwatcharachai, R.Greenwood, C.Ronco, N.W.Levin, " with the method and the repeatability of the resistivity in the local bioimpedance analysis measurement shank " (" Methods and reproducibility of measurement of resistivity in the calf usingregional), Blood Purif, the 21st volume; pp.131-136,2003

[10] Xitron Technologies, Inc., " 4000B bio-impedance spectrum analyzer system workbook ", first edition, San Diego, California, 1995, appendix A, 50-61 page or leaf.

Table 1

	Dielectric coefficient ε	The electricalresistivity (Ω-cm)
			Bone	640	10 4
Fat	3×10 4	1.5～5×10 3
			Blood	2.8×10 3	1.5×10 2
Muscle (parallel)	8×10 4	?2×10 2

Table 2

Object information

	On average	SD	Minimum	Maximum
					Sex	F9/M19
Age, year	53.4	?10.5	?33	?69
					Body weight, kg	80.4	?18	?43.2	?119.9
Height, cm	169.7	?9.5	?149	?184.9
					BMI，kg/m 2	27.7	?4.97	?19.18	?41.11
Fat, g	344.9	?118	?149.2	?533.5
					Muscle, g	525.3	?110.3	?326.5	?761.5

Table 3

VF/VG	ρ G，Mea(Ω-cm)	ρ * G，Cal(Ω-cm)	ρ G，Cal(Ω-cm)	Δρ (Ω-cm)
					＞0.2	?430.4±62	?359.9±43	?457.2±64	?70.5±24
≤0.2	?369.5±84	?322.7±57	?373.5±70	?46.8±29
					The p value	?＜0.05	?n.s.	?＜0.005	?＜0.05

ρ _{G, Cal}And ρ ^* _{G, Cal}It is respectively the resistivity value of calculating with equation 12 and 13; Δ ρ=ρ _{G, Mea}-ρ ^* _{G, Cal}The ρ E value of 90 Ω-cm is used to calculate ρ ^* _{G, Cal}And ρ _{G, Cal}

Table 4

The parameter that derives from curve fitting is summed up

Fat	P1	P2	P3	P4	Q1	Q2	Q3
								?G1	32.54± 5.9 *	1412± 262	-15330 ±3352	42640± 12130 +	22.5± 6.7	-276.4 ±76	649.8± 430
?G2	27.3± 3.7 *	1187± 548	-13012 ±3027	34166± 13808	22.6± 7.7	-262± 73	718 ± 372
								?G3	26±4.4	1168± 259	-10973 ±3448	24191± 16426 +	20.7± 8.7	-197.2 ±102	460.3± 460

^*With ⁺Remarkable (p＜0.05) difference between the expression group.

Claims (33)

1. the method for the bio-impedance data of a body segment that is used for analytic target, described body segment has the outer skin surface, and described method comprises:

(a) alternating current of a plurality of frequencies is put at least two points on outer skin surface, so that electric current passes this sections;

(b) for each frequency, the voltage difference between at least two other points in record outer skin surface, the voltage difference of described record comprise amplitude and mutually information; With

(c) the voltage difference that is used in a plurality of frequency records determines to show at least one numerical value of muscle, fat and/or the extracellular fluid content of this sections, described numerical value is to determine with the impedance model of this sections, this impedance model comprises three parallel circuit at least, and one of them circuit is by resistor R _IWith capacitor C _MBe composed in series, it mainly represents the muscle composition of this sections, and a circuit is by resistor R _FWith capacitor C _FBe composed in series, it mainly represents the fat constituent of this sections, and another circuit is made up of resistor.

2. the method for claim 1 is characterized in that, described at least one numerical value shows the muscle content of this sections, and obtains certainly R _IValue is converted into the dependency equation of this sections muscle content value.

3. method as claimed in claim 2 is characterized in that, described dependency equation is obtained by following steps:

(i) on a plurality of calibration object, carry out step (a), (b) with (c) to obtain the R of described each object _IValue;

(ii) on the sections of described a plurality of calibration object, carry out nuclear magnetic resonance to obtain the muscle content of described each object sections; With

(iii) step (i) and the (ii) middle numerical value that obtains are carried out regression analysis to obtain the dependency equation.

4. method as claimed in claim 3 is characterized in that, R in the dependency equation that described regression analysis produces ²Be at least 0.5.

5. method as claimed in claim 4 is characterized in that, described a plurality of calibration object comprise at least one body-mass index less than 20 calibration object and at least one body-mass index greater than 35 calibration object.

6. the method for claim 1 is characterized in that, described at least one numerical value shows the fat content of this sections, and obtains certainly R _FValue is converted into the dependency equation of this sections fat content value.

7. method as claimed in claim 6 is characterized in that, described dependency equation is obtained by following steps:

(i) on a plurality of calibration object, carry out step (a), (b) with (c) to obtain the R of described each object _FValue;

(ii) on the sections of described a plurality of calibration object, carry out nuclear magnetic resonance to obtain the fat content of described each object sections; With

(iii) step (i) and the (ii) middle numerical value that obtains are carried out regression analysis to obtain the dependency equation.

8. method as claimed in claim 7 is characterized in that, R in the dependency equation that described regression analysis produces ²Be at least 0.5.

9. method as claimed in claim 8 is characterized in that, described a plurality of calibration object comprise at least one body-mass index less than 20 calibration object and at least one body-mass index greater than 35 calibration object.

10. the method for claim 1 is characterized in that, the described parallel circuit of being made up of resistor is mainly represented the extracellular fluid composition of this sections.

11. the method for claim 1 is characterized in that, the described parallel circuit of being made up of resistor is mainly represented the parallel combination of the extracellular fluid and the bone component of this sections.

12. the method for claim 1 is characterized in that, described impedance model also comprises and described three parallel circuit series capacitors.

13. the method for claim 1 is characterized in that, described a plurality of frequencies comprise more than or equal to 5 kilo hertzs and are less than or equal to 1000 kilo hertzs frequency.

14. the method for claim 1 is characterized in that, the voltage of record is used to calculate the resistance value under each frequency condition in alternating current that applies in the described step (a) and the step (b), and step (c) comprises these resistance values are carried out curve fitting.

15. method as claimed in claim 14 is characterized in that,

(i) equation of following type has been adopted in described curve fitting:

Z wherein _AlwaysBe impedance, ω is the angular frequency of representing with the radian per second, $j=\sqrt{-1},$ P ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂And Q ₃Be the group parameter, described parameter is the function of the electricity composition that uses in the described impedance model; With

The P of the described object that (ii) from curve fitting, obtains ₁, P ₂, P ₃, P ₄, Q ₁, Q ₂And Q ₃Value is used for determining the R of this object _IValue and/or R _FValue.

16. the method for claim 1 is characterized in that, in step (a), at least two points on the described skin surface outside comprise:

(i) 2 points on the described object lower limb;

2 points on the (ii) described object shank;

2 points on the (iii) described object arm;

2 points on the (iv) described object biceps brachii m.;

(2 points on the v) described object abdominal part;

(a bit on any on the vi) described object left hand and the described object right hand;

(a bit on any on the vii) described object left foot and the described object right crus of diaphragm; Or

(a bit on any on hands of viii) described object or arm of described object and described object one leg or foot of described object.

17. the method for claim 1 is characterized in that, this method also comprises to user shows described at least one numerical value that shows muscle, fat and/or extracellular fluid content.

18. the method for claim 1 is characterized in that, described method is carried out on same target at two or more time points.

19. method as claimed in claim 18 is characterized in that, described method is implemented to be associated with following program:

(i) dialysis procedure;

(ii) degree of physical exercise;

(iii) rehabilitation procedure; And/or

(iv) body weight control program.

20. an instrument that is used to analyze the bio-impedance data, it comprises and is used to implement the computer that is composed of program of method according to claim 1.

21. a method that is used for the bio-impedance data of analytic target body segment, described body segment has the outer skin surface, and described method comprises:

(a) alternating current of a plurality of frequencies is put at least two points on outer skin surface, so that electric current passes this sections;

(b) for each frequency, the voltage difference between at least two other points in record outer skin surface, the voltage difference of described record comprise amplitude and mutually information; With

(c) the voltage difference that is used in a plurality of frequency records determines to show the fat of this sections and/or at least one numerical value of extracellular fluid content, described numerical value is determined with the impedance model of this sections, this impedance model comprises two parallel circuit at least, and one of them circuit is by resistor R _FWith capacitor C _FBe composed in series, it mainly represents the fat constituent of this sections, and another circuit is made up of the resistor of this sections extracellular fluid composition of main representative;

Wherein: (i) described two parallel circuit are only parallel circuit in this impedance model, and it represents the composition of skin inner segments; (ii) each frequency that applies in the step (a) is less than or equal to 10 kilo hertzs.

22. method as claimed in claim 21 is characterized in that, described at least one numerical value shows the fat content of this sections, and obtains certainly R _FValue is converted into the dependency equation of this sections fat content value.

23. method as claimed in claim 22 is characterized in that, described dependency equation is obtained by following steps:

(i) on a plurality of calibration object, carry out step (a), (b) with (c) to obtain the R of described each object _FValue;

(ii) on the sections of described a plurality of calibration object, carry out nuclear magnetic resonance to obtain the fat content of described each object sections; With

(iii) step (i) and the (ii) middle numerical value that obtains are carried out regression analysis to obtain the dependency equation.

24. method as claimed in claim 21 is characterized in that, in step (a), at least two points on the described skin surface outside comprise:

(i) 2 points on the described object lower limb;

2 points on the (ii) described object shank;

2 points on the (iii) described object arm;

2 points on the (iv) described object biceps brachii m.;

(2 points on the v) described object abdominal part;

(a bit on any on the vi) described object left hand and the described object right hand;

(a bit on any on the vii) described object left foot and the described object right crus of diaphragm; Or

(a bit on any on hands of viii) described object or arm of described object and described object one leg or foot of described object

25. method as claimed in claim 21 is characterized in that, this method also comprises to user shows described at least one numerical value that shows muscle, fat and/or extracellular fluid content.

26. method as claimed in claim 21 is characterized in that, described method is carried out on same target at two or more time points.

27. method as claimed in claim 26 is characterized in that, the enforcement of described method is associated with following program:

(i) dialysis procedure;

(ii) degree of physical exercise;

(iii) rehabilitation procedure; And/or

(iv) body weight control program.

28. an instrument that is used to analyze the bio-impedance data comprises the computer that is composed of program that is used to implement as method as described in the claim 21.

29. a method that is used to measure the girth of a body segment part that is covered by skin, this method comprises:

(a) described part around use a series of electrodes, described a series of electrodes have first electrode and the most last electrode, in described a series of electrodes, except that first and the most last distance between electrodes, the circumferential distance between all electrodes is known;

(b) by applying substantially the not low-frequency current of transdermal, measure in described a series of electrode except that first and the most last electrode resistance between at least two electrodes;

(c) determine the resistivity value of skin per unit length by known circumferential distance between the resistance measured in the step (b) and two electrodes;

(d) by applying substantially the not low-frequency current of transdermal, measure in described a series of electrode first and the most last electrode between resistance; With

(e) resistivity value by the per unit length measured in the resistance that records in the step (d) and the step (c) calculates in described a series of electrode first and the most last distance between electrodes.

30. method as claimed in claim 29 is characterized in that, except that first and the most last electrode, all adjacent electrodes between resistance measure by step (b), and be used for step (c) and measure resistivity value.

31. method as claimed in claim 29 is characterized in that, except that first and the most last electrode, adjacent electrode between distance equate.

32. method as claimed in claim 29 is characterized in that, described a series of electrodes are connected by belt.

33. an instrument that is used to measure the girth of a body segment part that is covered by skin, this instrument comprise the computer that is composed of program that is used to implement as method as described in the claim 29.

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